Frequencies for first 10,000 rows of pctpovr variable in nhamcsed2006 dataset :

 percent pop below poverty level in |
                 patient's zip code |      Freq.     Percent        Cum.
------------------------------------+-----------------------------------
quartile 1 (less than 5.00 percent) |      1,647       16.47       16.47
     quartile 2 (5.00-9.99 percent) |      2,611       26.11       42.58
   quartile 3 (10.00-19.99 percent) |      3,369       33.69       76.27
 quartile 4 (20.00 percent or more) |      1,928       19.28       95.55
                       missing data |        445        4.45      100.00
------------------------------------+-----------------------------------
                              Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016